Positioning technologies have been widely applied, for example, the Global Positioning System (GPS) technology has been very mature, and is widely applied to fields such as navigation. However, the GPS has low positioning precision; moreover, the GPS has weak signal strength in an indoor environment, and is not suitable for indoor applications. Therefore, in recent years, many positioning methods, apparatuses and systems that are suitable for indoor environments and different from the GPS are developed. For example, positioning is implemented by fading and a transmission delay characteristic of a signal such as electromagnetic waves (Bluetooth, WIFI and the like), sound and visible light during transmission over the air. Positioning may also be implemented according to different magnetic field distributions at different spatial positions. A direction and a distance from an object and a human body to a certain determined position may be deduced by tracking the movement of the object and the human with a gyroscope and an accelerator. Moreover, positioning may also be implemented according to an image shot by a camera and having some feature objects, where objects in the image have recognizable features and are located at specific positions, and therefore, the shot image may be recognized first, and positioning may be implemented by deducing the position of the camera apparatus according to the image.
Mobile terminals having camera functions are very popular recently, and are easy to implement. Therefore, the positioning method based on an image shot by a camera has many applications, for example, US patent applications No. US20120176491 A1 and US20120209513 A2 both propose positioning technologies based on an image shot by a camera.
However, the greatest problem of positioning based on an imaged shot by a camera is that: when the camera shoots an image, the position of the camera cannot be equivalent to the position of the shot image, and therefore, after the position of the shot image is determined, relative positions of the camera and the shot image need to be determined; otherwise, the positioning precision declines.